Set-back operated safety clutch



Jan. 31, 1956 c. J. HULL ETAL sm-aux OPERATED SAFETY CLUTCH 3 Sheets-Sheet. 1

Filed Nov. 4, 194'? 2 6 4 w 4 .1 W w 4 r J k K m M n u x "I! #L m v v n 4 a a z V M III. 7 8k L n u l J 6 |:;fl 4 E1 ROBERT ELTUTTL E,

a I ,L WW4 v Jan. 31, 1956 c. J. HULL EI'AL 2,732,801

SET-BACK OPERATED SAFETY CLUTCH Filed NOV'. 4, 1947 3 Sheets-Sheet 2 3 W0 Mom.

EHARLEE. Ll HULL, ROBERT E 1111-1115 Filed Nov. 4, 1947 Jan. 31, 1956 c. J. HULL ETAL 2,732,801

SET-BACK OPERATED SAFETY CLUTCH 3 Sheets-Sheet 3 CHARLES J. HLIL ROBERT ELTu-rTLs;

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e State fa m fofi e 2,732,801 f ed -1 3'} 5?.

V 2,732,801" SET-BACK OPERATED SAFETY CLUTCH Charles J. Hull and Robert S. Tuttle, Eggertsville, N. Y.,

assignors to the United States of America as represented by theSecretary of War Application November 4, 1947, Serial No. 783,896

2 Claims. (c1. 102 7s such rotation being utilized for a variety of purposes in connection with the operation of the fuze, such as rotation of a gear train toactuate a powder train interrupter of known construction, and to operate a self-destruction switch after a suitable time interval, driving a generator to supply electric power etc. Such fuzes are known in the art, and are not pers e an objecto'f the present invention which relates specifically to set-back operated-safety clutch means fora rotating shaft such as above described.

An object of our invention is to provide means retaining said drive shaft against operative rotation except after the projectile, of which it is a part, has been properly discharged, while permitting limited rotation of said shaft for test or other desired purposes. It is also an object to provide means for preventing operative engagement of said drive shaft with at least a part of its driven mechanism until the projectile has been properly discharged.

It is also an object of our invention to provide said means by the use of simple, easily fabricated parts of inexpensive construction.

Additional objectives, advantages and features of invention reside in the construction, arrangement and combination of parts involved in the embodiment of our invention as will appear or be understood from the following description and accompanying drawings, wherein:

Fig. 1 is a longitudinal section taken on line l1 of Fig. 2, of a projectile embodying our invention,

Fig. 2 is a transverse sectional view of the same projectile taken on line 2-2 of Fig. 1.

Fig. 3 is a longitudinal view in partial section of the same projectile showing a detail of the set-back time delay mechanism, taken on line 3-3 of Fig. 2.

Fig. 4 is a view similar to Fig. 2, showing the mechanism after normal operation, and

Fig. 5 is a view similar to Fig. 1 of a detail of the mechanism after normal operation.

Referring to the drawings, the casing 1 contains the fuze mechanism and may be of any desired or known size and configuration, adapted to the projectile with which it is to be used, which is intended to be projected in the direction shown by the arrow in Fig. 1 by any suitable launching or firing apparatus for the projectile, which may be of either the rocket or the shell type. These details are well understood in the art and are no part of our invention. Supported for rotation centrally of casing 1 is shaft 11, which, when the projectile is in flight, it is desired to rotate by suitable means such as a windvane (not shown) on the forward or exposed end of the fuze, or by any other suitable means. The driving means for the shaft, and the projectile in which the fuze is to be used are not shown, as these features are well understood by t 2 t those skilled in this art and form no partof the present invention.

Shaft 11 is intended to be rotated in the direction shown by the arrow in Figs. 1 and 2 and may be supported in suitable bearings 12 and 13 which may be of any suitable construction. Located on the shaft between bearings 12 and 13 may be a suitable generator which is schematically indicated at 14, the details of construction 'of this portion of the fuze being no part of the present invention. Shaft 11 has fixed thereto a spur gear 3 which engages another spur gear'2 mounted for rotation on stubshaft 23, Frie tion plates 4 are held against the sides of spur gear 2 spring Washer 5 and are retained against rotation by stationary pin 15 (Fig. 4). a This spring washer- 5 isretaine'd by the latch washer 6 and spring ring 7. The 'two' gears are urged into engagement by the set back spring 8. At the time of set-back the set-back spring 8is compressed sufiiciently to disengage the spur gears 2 and 3 when an acceleration force of approximately 10 g. or more" exists. This will allow the drive shaft l l'to rotate,which'it will do because of the windvane 'or otherpropelling means act inguponit. p

'If the acceleration force (dueto set-back) rises to the vicinity'of g. and maintains this force for'app roxi mately 3 second, which will be the case 'on normal discharge of the projectile, the set-back mechanism 9 (Figs; 2 and 3) will operate. Thismechanisrn, which is not part of our invention, except in the association shown with the elements hereinafter described, comprises a toothed wheel 16 provided with an eccentric weight: 17 so" located with respect to'the line offlight that the acceleration force on this unbalanced weight tends to drive wheel 16 counterclockwise as viewed in Fig. 3. This motion is retarded by escapement 18 which has two pins 19 coacting with the teeth of wheel 16 to delay rotation thereof in wellknown fashion so that it will require a force of 100 g. acting for at least A second to rotate wheel 16 sufficiently to bring weight 17 into the lowest position (with reference to Fig. 3) that it can assume. If the acceleration (or set-back) force subsides before this position is reached, spring 21 will then return the wheel 16 to its original position. If the wheel 16 moves to its extreme position, this will align hole 22 in the wheel with pin 10 (Fig. 2) which will then snap through hole 22, under the influence of spring 24. This accomplishes three things: First, it prevents wheel 16 from returning to its original position, even though the set-back force subsides. Second, it causes latch 25 to move into the return path of latch washer 6 which was displaced rearwardly by the same force which moved wheel 16, so that washer 6 cannot thereafter return to cause engagement of spur gears 2 and 3. Third, pin 10 moves out of the way of element 26 of safety clutch 20, permitting this element under the action of spring 28 to engage cooperating plate 30 of clutch 20 so that this safety clutch, through pinion gear 32, which is driven by a worm 27 (Fig. l) on drive shaft 11, becomes effective to drive the slow-speed safety arming and selfdestruction mechanism generally shown at 34 (Fig. 1), through gear train 36. The latter part of the arming system is not our invention and may be such, for example, as is shown in the copending application of Allen S. Clarke et al. for Generator Powered Fuze, filed on even date herewith.

This will in most cases include a powder train interrupter and may include a self-destruction arrangement which is actuated after the projectile has gone a suflicient distance so that after the target (in the case of aerial target such as an airplane) has clearly been missed, the projectile will be exploded in the air and before it is close to the ground. Thus the projectile will be prevented from exploding on friendly territory (in the caseof antiaircraft fire), or from falling into enemy hands (if discharged over enemy territory) as the case may be.

The purpose of the friction clutch comprising friction plates 4and; spring washer 5 and the safety clutch 20 is to permit forced rotation of the drive shaft 11, as is-often donetby -unskilled personnel, without resultant damage. Such :damage would otherwise result when theshaft-is rotated while'the mechanism is in safety locked position due-to -the enormous mechanical advantage of-the gear train 'required'or the safetyarming and self-destruction mechanism, and because of the relative fragility 'of'the parts necessitated by-thesmall-size of the fuze and by the functional-requirement ofits operation. Our construction also permits a limited amount of testing of the dynamic components of the fuze-associated with 'the-drive shaft 11,;by permitting a limited amount of rotation of said shaft; -yetnormal rotation of the shaft is prevented untilset-back due to normal-firinghas taken place. lt will be apparent,;moreover,-that:the preset arming time of the fuze will not be affected-by such forced '-rotation of the drive-shaft.

' We claim: I

1. lna fuze mechanism comprising a drive shaft-adapted for rotation-at highspeed during normal free-flightoperation to drive a low speed arming mechanism through a gear train; the combination of'an assembly comprising a friction clutch embracing a spur gear driven by said drive shaft-to oppose a predetermined friction load to such motion,said friction clutch and gear'slidablymounted on a stub shaft spaced from and parallel to said drive shaft, said: spur gear dise'ngaging the drive shaft upon set-back, a safety clutch for operatively transmitting powerfrom said driveshaft to said armingmechanism and biased toward operative position, set-back'mechanism operatively connected with said safety clutch, a spring biased pin having one end in releasable engagement with said safety clutch and its opposite end in engagement with said setback mechanism, said pin biased toward said set-back mechanism to permit functioning of said safety clutch upon set-back, and a latch pivotally mounted intermediate said biased pin and said friction clutch, one end of said latch coupled to said biased pin intermediate the ends thereof and the opposite end positioned to engage said friction clutch upon set-backand thereby maintain disengagement of said -spur gear and'drive-shaft.

2. The invention according to claim 1 wherein said setback mechanism comprises a t'ooth'ed wheel having a trans verse hole formed therein for receiving the said opposite end of the biased pin, an 'eccentric'weig'ht aflixed to said wheel, an escapement provided with pins cooperating with the teeth of said wheel, said weight upon set-back rotating the wheelandcausing alignment of the transversehole and biased pin, said pin thereupon 'moving-toward and engaging said hole thereby preventing further movement of said Wheel and to release said safety clutch permitting functioning of said'low-speed arming mechanism, saidipin during its movement into engagement with said hole causing said'latch to engage said assembly and thereby maintain disengagement of saidspur gear and'drive shaft.

References Cited in the file of this patent UNITED STATES PATENTS 568,527 Pearson Jan. 5, 1926 15:69:91], Bold Jan. 19, 1926 2376,0230 'Perry et a1 May 15, 1945 2,397,055 "Sekella Mar. 19, 1946 

